Field
The disclosed technology relates to methods, apparatuses and systems for detecting molecules using surface plasmon resonance techniques, and more particularly to surface plasmon resonance techniques that employ metal particles formed on substrates.
Description of the Related Art
A surface plasmon (SP) refers to coherent electron oscillation that propagates along an interface between a dielectric (e.g. silica glass) and a metal (e.g. Ag or Au) together with an electromagnetic wave, e.g., light. Under certain conditions (defined by of wavelength, polarization and/or incidence angle), free electrons at the surface of the metal absorb incident light photons and convert them into surface plasmon waves. A resonance condition, referred to as surface plasmon resonance (SPR), can be established when the frequency of light photons matches the natural frequency of surface electrons oscillating against the restoring force of positive nuclei of the metal. The SPR condition can be used to for in optical measurements such as fluorescence, Raman scattering, second harmonic generation, and absorption, among others.